Definition: Dependence of a variable 
from a variable 
is called a functionif each value corresponds to a single value .
A function is identified by either a single letter 
, (or 
), or equality 
.
Definition: a Numeric function with a domain of definition 
is the relationship in which each number from the set is assigned a single number , which of course affects .
Terms: independent variable, or argument, independent variable, or function, 
—the value of the function at the point 
The domain of the function
Definition: the domain of the function 
— the set of values that can take the argument.
Example of finding the area of a function definition
Scope (S): 
that is 
Many of the function values
Definition: the set of function values 
the set of values that can take the function at all values of the argument from scope (it is all values >m>aunder which the equation 
has a junction).
Example of finding the set of values of the function
Number of values: 
since 
for all 
and takes all values from 0 to 